NEWARK, N.J. (AP)  Newark will test up to 17,000 children for lead poisoning after elevated levels of the toxin were found in the drinking water at nearly half of the schools in New Jersey”s biggest city.

City Health Director Hanaa Hamdi told officials Tuesday that testing will start with some 2,000 toddlers who attend early childhood centers. A specific date hasn”t been set yet to get blood samples from the children.

Lead is known to severely affect a child”s development.

In the week since the higher lead levels were first reported, officials have urged calm. They say the lead levels in some of Newark”s schools don”t compare to the crisis that has plagued Flint, Michigan.

Gov. Chris Christie said Tuesday his administration would work closely with Newark officials to help remedy the problem. The commissioner of the state”s Department of Environmental Protection is working directly with the superintendent of Newark schools, he said.

“I want to make sure everyone understands this is a situation we”re concerned about, but it is not a crisis,” Christie said to reporters in Linden, New Jersey. “But we don”t want to let it become a crisis. So we”re on top of it.”

It”s unclear how long Newark”s kids have been exposed to higher concentrations of lead. Schools had shut off the water at 30 school buildings last week. They are now using bottled water for drinking and cooking.

Officials said they don”t believe the contamination poses any serious health risks. The DEP has said that lead hasn”t been found in the city”s water supply. It likely leached into the schools” water through lead pipes or other building fixtures made of lead or lead solder.